Book/Report

FZJ-2018-01461

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Crystal structure investigations on cation-substituted alums by x-ray and neutron diffraction

Abdeen, A. M. (Corresponding author)FZJ*

1980
Kernforschungsanlage Jülich, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/17483

Report No.: Juel-1653

Abstract: The crystal structures of the three alums: NH$_{4}$Al(SO$_{4}$) $_{2}$.12H$_{2}$O, (NH$_{3}$CH$_{3}$)Al(S=$_{4})_{2}$.12H$_{2}$O and (NH$_{3}$OH)Al(SO$_{4})_{2}$.12H$_{2}$O have been determined from three-dimensional neutron diffraction data enhanced by X-ray diffraction when necessary. These compounds crystallize cubic in space group Pa3. The structures of the three alums exhibit partial occupancies of crystallographic sites for the NH$_{4}$, (NH$_{3}$CH$_{3}$) and (NH$_{3}$OH) group atoms. This can be explained by a quantized rotation of the three groups around an axis perpendicular to the [111] direction. Some of the (SO$_{4})^{2-}$ groups in the NH$_{4}$-alum are disoroered with about 17% of the sulfate tetrahedra being in a reversed orientationaround the sulfur atom. The disorder in (NH$_{3}$CH$_{3}$ ) and (NH$_{3}$OH)-alums is only 4,3% and 3.0% respectively. The atoms in the alum structures are held together by a system of hydrogen borxis between the water molecules and between the water molecules and the sulfate oxygen atoms. In these three structures there is a strong indication that shorter hydrogen bonds tend to be nearly linear.

---

Contributing Institute(s):

1. Publikationen vor 2000 (PRE-2000)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

---

Database coverage:

---